Federation API for Space summary

synapse/federation/transport/server.py

@@ -18,7 +18,7 @@
 import functools
 import logging
 import re
-from typing import Optional, Tuple, Type
+from typing import TYPE_CHECKING, Container, Mapping, Optional, Sequence, Tuple, Type
 
 import synapse
 from synapse.api.constants import MAX_GROUP_CATEGORYID_LENGTH, MAX_GROUP_ROLEID_LENGTH
@@ -29,7 +29,7 @@
     FEDERATION_V1_PREFIX,
     FEDERATION_V2_PREFIX,
 )
-from synapse.http.server import JsonResource
+from synapse.http.server import HttpServer, JsonResource
 from synapse.http.servlet import (
     parse_boolean_from_args,
     parse_integer_from_args,
@@ -44,10 +44,14 @@
     whitelisted_homeserver,
 )
 from synapse.server import HomeServer
-from synapse.types import ThirdPartyInstanceID, get_domain_from_id
+from synapse.types import JsonDict, ThirdPartyInstanceID, get_domain_from_id
+from synapse.util.ratelimitutils import FederationRateLimiter
 from synapse.util.stringutils import parse_and_validate_server_name
 from synapse.util.versionstring import get_version_string
 
+if TYPE_CHECKING:
+    import synapse.server
+
 logger = logging.getLogger(__name__)
 
 
@@ -1376,6 +1380,40 @@ async def on_PUT(self, origin, content, query, group_id):
         return 200, new_content
 
 
+class FederationSpaceSummaryServlet(BaseFederationServlet):
+    PREFIX = FEDERATION_UNSTABLE_PREFIX + "/org.matrix.msc2946"
+    PATH = "/spaces/(?P<room_id>[^/]*)"
+
+    async def on_POST(
+        self,
+        origin: str,
+        content: JsonDict,
+        query: Mapping[bytes, Sequence[bytes]],
+        room_id: str,
+    ) -> Tuple[int, JsonDict]:
+        suggested_only = content.get("suggested_only", False)
+        if not isinstance(suggested_only, bool):
+            raise SynapseError(
+                400, "'suggested_only' must be a boolean", Codes.BAD_JSON
+            )
+
+        exclude_rooms = content.get("exclude_rooms", [])
+        if not isinstance(exclude_rooms, list) or any(
+            not isinstance(x, str) for x in exclude_rooms
+        ):
+            raise SynapseError(400, "bad value for 'exclude_rooms'", Codes.BAD_JSON)
+
+        max_rooms_per_space = content.get("max_rooms_per_space")
+        if max_rooms_per_space is not None and not isinstance(max_rooms_per_space, int):
+            raise SynapseError(
+                400, "bad value for 'max_rooms_per_space'", Codes.BAD_JSON
+            )
+
+        return 200, await self.handler.federation_space_summary(
+            room_id, suggested_only, max_rooms_per_space, exclude_rooms
+        )
+
+
 class RoomComplexityServlet(BaseFederationServlet):
     """
     Indicates to other servers how complex (and therefore likely
@@ -1474,18 +1512,24 @@ async def on_GET(self, origin, content, query, room_id):
 )
 
 
-def register_servlets(hs, resource, authenticator, ratelimiter, servlet_groups=None):
+def register_servlets(
+    hs: "synapse.server.HomeServer",
+    resource: HttpServer,
+    authenticator: Authenticator,
+    ratelimiter: FederationRateLimiter,
+    servlet_groups: Optional[Container[str]] = None,
+):
     """Initialize and register servlet classes.
 
     Will by default register all servlets. For custom behaviour, pass in
     a list of servlet_groups to register.
 
     Args:
-        hs (synapse.server.HomeServer): homeserver
-        resource (JsonResource): resource class to register to
-        authenticator (Authenticator): authenticator to use
-        ratelimiter (util.ratelimitutils.FederationRateLimiter): ratelimiter to use
-        servlet_groups (list[str], optional): List of servlet groups to register.
+        hs: homeserver
+        resource: resource class to register to
+        authenticator: authenticator to use
+        ratelimiter: ratelimiter to use
+        servlet_groups: List of servlet groups to register.
             Defaults to ``DEFAULT_SERVLET_GROUPS``.
     """
     if not servlet_groups:
@@ -1500,6 +1544,14 @@ def register_servlets(hs, resource, authenticator, ratelimiter, servlet_groups=N
                 server_name=hs.hostname,
             ).register(resource)
 
+        if hs.config.experimental.spaces_enabled:
+            FederationSpaceSummaryServlet(
+                handler=hs.get_space_summary_handler(),
+                authenticator=authenticator,
+                ratelimiter=ratelimiter,
+                server_name=hs.hostname,
+            ).register(resource)
+
     if "openid" in servlet_groups:
         for servletclass in OPENID_SERVLET_CLASSES:
             servletclass(

synapse/handlers/space_summary.py

@@ -56,7 +56,7 @@ async def get_space_summary(
         max_rooms_per_space: Optional[int] = None,
     ) -> JsonDict:
         """
-        Implementation of the space summary API
+        Implementation of the space summary C-S API
 
         Args:
             requester:  user id of the user making this request
@@ -110,9 +110,65 @@ async def get_space_summary(
 
         return {"rooms": rooms_result, "events": events_result}
 
+    async def federation_space_summary(
+        self,
+        room_id: str,
+        suggested_only: bool,
+        max_rooms_per_space: Optional[int],
+        exclude_rooms: Iterable[str],
+    ) -> JsonDict:
+        """
+        Implementation of the space summary Federation API
+
+        Args:
+            room_id: room id to start the summary at
+
+            suggested_only: whether we should only return children with the "suggested"
+                flag set.
+
+            max_rooms_per_space: an optional limit on the number of child rooms we will
+                return. Unlike the C-S API, this applies to the root room (room_id).
+                It is clipped to MAX_ROOMS_PER_SPACE.
+
+            exclude_rooms: a list of rooms to skip over (presumably because the
+                calling server has already seen them).
+
+        Returns:
+            summary dict to return
+        """
+        # the queue of rooms to process
+        room_queue = deque((room_id,))
+
+        # the set of rooms that we should not walk further. Initialise it with the
+        # excluded-rooms list; we will add other rooms as we process them so that
+        # we do not loop.
+        processed_rooms = set(exclude_rooms)  # type: Set[str]
+
+        rooms_result = []  # type: List[JsonDict]
+        events_result = []  # type: List[JsonDict]
+
+        while room_queue and len(rooms_result) < MAX_ROOMS:
+            room_id = room_queue.popleft()
+            logger.debug("Processing room %s", room_id)
+            processed_rooms.add(room_id)
+
+            rooms, events = await self._summarize_local_room(
+                None, room_id, suggested_only, max_rooms_per_space
+            )
+
+            rooms_result.extend(rooms)
+            events_result.extend(events)
+
+            # add any children that we haven't already processed to the queue
+            for edge_event in events:
+                if edge_event["state_key"] not in processed_rooms:
+                    room_queue.append(edge_event["state_key"])
+
+        return {"rooms": rooms_result, "events": events_result}
+
     async def _summarize_local_room(
         self,
-        requester: str,
+        requester: Optional[str],
         room_id: str,
         suggested_only: bool,
         max_children: Optional[int],
@@ -144,12 +200,25 @@ async def _summarize_local_room(
             )
         return (room_entry,), events_result
 
-    async def _is_room_accessible(self, room_id: str, requester: str) -> bool:
-        try:
-            await self._auth.check_user_in_room_or_world_readable(room_id, requester)
+    async def _is_room_accessible(self, room_id: str, requester: Optional[str]) -> bool:
+        # if we have an authenticated requesting user, first check if they are in the
+        # room
+        if requester:
+            try:
+                await self._auth.check_user_in_room(room_id, requester)
+                return True
+            except AuthError:
+                pass
+
+        # otherwise, check if the room is peekable
+        hist_vis = ""
+        hist_vis_ev = await self._state_handler.get_current_state(
+            room_id, EventTypes.RoomHistoryVisibility, ""
+        )
+        if hist_vis_ev:
+            hist_vis = hist_vis_ev.content.get("history_visibility")
+        if hist_vis == HistoryVisibility.WORLD_READABLE:
             return True
-        except AuthError:
-            pass
 
         logger.info(
             "room %s is unpeekable and user %s is not a member, omitting from summary",